In the process of producing a semiconductor device such as IC and LSI, fine processing by lithography using a photoresist composition has been conventionally performed. Recently, the integration degree of an integrated circuit is becoming higher and formation of an ultrafine pattern in the sub-micron or quarter-micron region is required. To cope with this requirement, the exposure wavelength also tends to become shorter, for example, from g line to i line or further to KrF excimer laser light. At present, other than the excimer laser light, development of lithography using electron beam, X ray or EUV light is proceeding.
The lithography using electron beam or EUV light is positioned as a next-generation or next-next-generation pattern formation technique and a high-sensitivity, high-resolution resist is being demanded. Particularly, in order to shorten the wafer processing time, elevation of the sensitivity is very important, but when high sensitivity of a positive resist for use with electron beam or EUV is sought for, not only reduction in the resolution but also worsening of the line width roughness (LWR) are incurred and development of a resist satisfying these properties at the same time is strongly demanded. High sensitivity, high resolution and good LWR are in a trade-off relationship and it is very important how to satisfy these properties at the same time.
Also in the lithography using ArF or KrF excimer laser light, it is similarly an important problem to satisfy all of high sensitivity, high resolution and good LWR.
Furthermore, in the process as typified by a contact hole process, sidelobe margin, exposure latitude (EL), depth-of-focus (DOF) performance and profile are raised as problems to be solved. In particular, as for the sidelobe margin, mere elevation of contrast also involves elevation of sensitivity to sidelobe light, resulting in a trade-off relationship with the exposure latitude (EL). It is very important how to satisfy these properties all at the same time.
Here, the sidelobe margin is a phenomenon such that phase shifting due to use of a phase shift mask called a halftone mask, which is generally performed in recent years for raising the resolution when resolving contact holes, allows slight light transmission through an originally unintended part to form a groove on the side of a hole. This groove is likely to be transferred to a substrate by an etching process and if the sidelobe resistance is poor, an electrical characteristic failure is brought about to reduce the yield.
As regards the resist suitable for such a lithography process using KrF excimer laser light, electron beam or EUV light, a chemical amplification-type resist utilizing an acid catalytic reaction is mainly used from the standpoint of elevating the sensitivity and in the case of a positive resist, a chemical amplification-type resist composition mainly comprising an acid generator and a phenolic polymer which is insoluble or sparingly soluble in an alkali developer but becomes soluble in an alkali developer by the action of an acid (hereinafter simply referred to as a “phenolic acid-decomposable resin”), is being effectively used.
As regards the resist for electron beam or X-ray, a resist technique for KrF excimer laser has been heretofore mainly utilized and studied. For example, there are disclosed a combination of a compound capable of generating an acid upon irradiation with electron beams and an amine compound having a boiling point of 250° C. or less in JP-A-2000-181065 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), a combination use of an acid-decomposable group-containing polymer, an acid generator and an electron beam sensitizer in European Patent 0919867, a tertiary amine compound having an ether bond in JP-A-10-326015, and a combination use of an amide compound in JP-T-7-508840 (the term (the term “JP-T” as used herein means a “published Japanese translation of a PCT patent application”). Furthermore, JP-A-3-200968 discloses a maleimide compound, JP-A-7-92680 discloses a sulfonamide compound, JP-A-11-44950 discloses a sulfonimide compound containing an —SO2—NH—SO2— partial structure, and JP-A-2003-98672 discloses an oxygen-containing aliphatic amine. However, at present, none of these attempts for improvement has succeeded in satisfying high resolution, good sidelobe margin, exposure latitude (EL), depth-of-focus (DOF) performance and profile all at the same time.